The present invention relates generally to vegetation trimming and edging devices and, more particularly, to mechanisms for adjustment between trimming and edging modes.
Many vegetation trimming and edging devices make use of a cutting element, such as a plastic string, that is rotated at high speed to cut vegetation such as grass or weeds. Trimming generally refers to the cutting of vegetation in a substantially horizontal swath. Edging generally refers to the cutting of vegetation with a substantially vertical swath to produce a more precise edge, e.g., for defining the border of a lawn adjacent a driveway or sidewalk.
The user adjusts the cutting device between horizontal and vertical orientations for trimming or edging. Physically tilting the cutting device to the proper orientation can be awkward, however, and cause muscle strain. For this reason, many cutting devices offer an adjustable working member, or xe2x80x9chead,xe2x80x9d that can be manipulated between the trimming and edging positions.
The head is mounted at the end of a shaft that extends from the head to a handle that is gripped by the user. The head typically contains a motor and a rotor to which the cutting element is attached. The handle includes a switch for actuation of the motor. By rotating the head about the shaft, the user can adjust the orientation of the cutting element, but maintain the orientation of the handle gripped by the user.
The present invention is directed to a vegetation trimming and edging device having an adjustable head that permits selective positioning between trimming and edging orientations. A shaft extends between the head and a handle. The head receives one end of the shaft. A coupling mechanism couples the head and shaft, and locks the head against rotational movement about the shaft. In particular, the coupling mechanism includes a locking structure and a bias mechanism.
The bias mechanism urges the locking structure into engagement to prevent rotational movement of the head. Downward pressure applied to the head overcomes the bias, however, and disengages the locking mechanism for rotation of the head between trimming and edging modes. When the downward pressure is released, the locking mechanism is again engaged to lock the head in position for the desired operational mode.
In some embodiments, the coupling mechanism faciliates a xe2x80x9cpush-and-turnxe2x80x9d operation in which the head is forced downward against a bias, and then rotated to a rotational position appropriate for trimming or edging. This xe2x80x9cpush-and-turnxe2x80x9d arrangement reduces the possibility that the head will unexpectedly rotate during use, as could occur with a xe2x80x9cpull-and-turnxe2x80x9d arrangement in which upward movement of the head permits rotation. In particular, contact of the head with the ground and resulting upward movement is less likely to cause rotation. This may be particularly advantageous for bump-feed devices.
In other embodiments, the coupling mechanism may include a locking collar that can be moved upward to free the head for rotational movement between trimming and edging positions. For this arrangement, axial movement of the head is unecessary for rotation. Thus, unlike a pull-and-turn arrangement, upward movement of the head is unlikely to cause unexpected rotational movement. Instead, the locking collar generally requires manual intervention to permit rotation of the head, thereby resisting rotation due to head-ground contact.
In one embodiment, the present invention provides a vegetation trimming and edging device comprising a cutting element, a motor that drives the cutting element, a head that supports the motor and the cutting element, a handle, a shaft extending between the head and the handle, and a coupling mechanism that couples the shaft to the head, the coupling mechanism including an opening defined by the head for receipt of the shaft, a structure extending from one of the head and the shaft, a track defined by one of the head and the shaft, the track extending in a substantially circumferential direction relative to the shaft, wherein the structure travels along the track during rotation of the head about a longitudinal axis defined by the shaft, a first slot defined by the track for receipt of the structure at a first rotational position of the head appropriate for edging operation, a second slot defined by the track for receipt of the structure at a second rotational position of the head appropriate for trimming operation, and a bias mechanism that biases the structure into engagement with the first slot upon rotation of the head into the first rotational position, and biases the structure into engagement with the second slot upon rotation of the head into the second rotational position, whereby one of the first and second slots locks the head against rotation, and the head is rotatable between the first and second rotational positions upon movement of the structure against the bias and out of engagement with the respective slot.
In another embodiment, the present invention provides a coupling mechanism for coupling a shaft to a head in a vegetation trimming and edging device, the coupling mechanism comprising an opening defined by the head for receipt of the shaft, a structure extending from one of the head and the shaft, a track defined by one of the head and the shaft, the track extending in a substantially circumferential direction relative to the shaft, wherein the structure travels along the track during rotation of the head about a longitudinal axis defined by the shaft, a first slot defined by the track for receipt of the structure at a first rotational position of the head appropriate for edging operation, a second slot defined by the track for receipt of the structure at a second rotational position of the head appropriate for trimming operation, and a bias mechanism that biases the structure into engagement with the first slot upon rotation of the head into the first rotational position, and biases the structure into engagement with the second slot upon rotation of the head into the second rotational position, whereby one of the first and second slots locks the head against rotation, the head being rotatable between the first and second rotational positions upon movement of the structure against the bias and out of engagement with the respective slot.
In a further embodiment, the present invention provides a vegetation trimming and edging device comprising a head that supports a cutting element, a shaft mounted in an opening defined by the head, a structure extending from one of the head and the shaft, a track defined by one of the head and the shaft opposite the structure, the structure traveling along the track upon rotation of the head, first and second slots formed at different positions along the track, and a mechanism that urges the structure into one of the first and second slots to thereby lock the head against rotation.
In an added embodiment, the present invention provides a coupling mechanism for coupling a shaft to a head in a vegetation trimming and edging device, the coupling mechanism comprising a structure extending from one of the head and the shaft, a track defined by one of the head and the shaft opposite the structure, the structure traveling along the track upon rotation of the head, first and second slots formed at different positions along the track, and a mechanism that urges the structure into one of the first and second slots.
In another embodiment, the present invention provides a vegetation trimming and edging device comprising a cutting element, a motor that drives the cutting element, a head that supports the motor and the cutting element, a handle, a shaft extending between the head and the handle, and a coupling mechanism that couples the shaft to the head, the coupling mechanism including a neck portion defined by the head for receipt of the shaft, a collar mounted about the neck portion and about a portion of the shaft proximate the neck portion, the neck portion and collar having a keyed structure such that the collar and neck portion are jointly rotatable about the shaft, a structure extending from one of an exterior surface of the shaft and an interior surface of the collar, a slot defined by one of the collar and the shaft for engagement with the structure to lock the collar and neck portion against rotation about the shaft, and a bias mechanism that biases the structure and slot into engagement with one another upon rotation of the collar and head to a first rotational position, the structure and the slot lock the collar and the head against rotation, the head being rotatable between the first and second rotational positions upon movement of the collar against the bias to disengage the structure and slot.
In a further embodiment, the present invention provides a coupling mechanism for coupling a shaft to a head in a vegetation trimming and edging device, the coupling mechanism comprising a neck portion defined by the head for receipt of the shaft, a collar mounted about the neck portion and about a portion of the shaft proximate the neck portion, the neck portion and collar having a keyed structure such that the collar and neck portion are jointly rotatable about the shaft, a structure extending from one of an exterior surface of the shaft and an interior surface of the collar, a slot defined by one of the collar and the shaft for engagement with the structure to lock the collar and neck portion against rotation about the shaft, and a bias mechanism that biases the structure and slot into engagement with one another upon rotation of the collar and head to a first rotational position, the structure and the slot lock the collar and the head against rotation, the head being rotatable between the first and second rotational positions upon movement of the collar against the bias to disengage the structure and slot.
In an added embodiment, the present invention provides a vegetation trimming and edging device comprising a head that supports a cutting element, a shaft, a neck portion defined by the head for receipt of the shaft, a collar mounted about the neck portion and about a portion of the shaft proximate the neck portion, the neck portion and collar being jointly rotatable about the shaft, a structure extending from one of the shaft and the collar, a slot defined-by one of the collar and the shaft for engagement with the structure to lock the collar and neck portion against rotation about the shaft, and a bias mechanism that biases the structure and slot into engagement with one another upon rotation of the collar and head to a first rotational position, the structure and the slot locking the collar and the head against rotation, the head being rotatable between the first and second rotational positions upon movement of the collar against the bias to disengage the structure and slot.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.